Study of SLS009 (Formerly GFH009) a Potent Highly Selective CDK9 Inhibitor in Patients With Hematologic Malignancies and High-Risk Newly Diagnosed AML

Inclusion Criteria

For Groups 1, 2, 3, 4 and 5:

Patients eligible for inclusion must meet all of the following criteria:

1. Male or female ≥ 18 years. For Group 3 Cohorts 4 and 5 only male or female ≥18 years and pediatric patients 12-18 years and ≥40 kg body mass

2. Written informed consent must be obtained prior to any screening procedures

3. For AML, acute promyelocytic leukemia (APL) patients are not included in the study.

4. Adequate hepatic function as evidenced by meeting all the following requirements:

• Total bilirubin ≤ 1.5 × upper limit of normal (ULN) except for patients with Gilbert's syndrome, who are included if total bilirubin is < 3 × ULN or if direct bilirubin is < 1.5 × ULN.

• Aspartate aminotransferase (AST), alanine aminotransferase (ALT) ≤2.5 × ULN. For those with hepatic metastases, AST and ALT ≤ 5 ×ULN.

5. Measured or calculated (determined by the Cockcroft-Gault equation) serum creatinine clearance (CrCl) ≥ 60 mL/min (glomerular filtration rate can be alternative to CrCl) for adult patients or serum creatinine ≤ 1.5 x ULN; or if serum creatinine > 1.5 x ULN, then serum creatinine clearance (CrCl) ≥ 50 mL/min (estimated by Cockcroft-Gault formula or other appropriate formula) for pediatric patients. Whether the value is calculated by equation or measured directly can be based on institutional standard practice.

6. Amylase ≤ 1.5 × ULN.

7. Eastern cooperative oncology group (ECOG) performance status 0-2.

8. The electrolytes and uric acid level need to be stable judged by investigators for at least 3 days before the first dose of GFH009 (Medical intervention is permitted).

For AML and other leukemias:

• Peripheral WBC counts < 50,000/µL. Cytoreduction prior to study will be allowed with hydroxyurea; hydroxyurea use will also be permitted during treatment period in patients with proliferative, progressive disease. Use of leukapheresis for the purpose of lowering WBC counts to make the patient eligible for enrolment is not permitted.

9. Recovery to grade 0-1 from adverse events related to prior anti-tumor therapy except alopecia, fatigue, < Grade 2 sensory neuropathy and endocrinopathies controlled with hormone replacement therapy.

10. For women of childbearing potential, she must consent to use highly effective methods (e.g., total abstinence, placement of an intrauterine device) of contraception during GFH009 treatment and for an additional 90 days after the last administration of study drug if enrolled in Group 1 and 2, and 6 months enrolled in Group 3.

Men with a partner of childbearing potential, must consent to use highly effective methods of contraception during GFH009 treatment and for an additional 90 days after the last administration of study drug.

For Groups 1, 2 and 3:

Patients eligible for inclusion must meet all of the following criteria:

1. Male or female ≥ 18 years. Pediatric patients ages 12-18 and ≥40 kg body mass.

2. Patients with cytological or histologically confirmed relapsed or refractory hematologic malignancies (AML, CLL/SLL and lymphoma):

• For Lymphoma, Burkitt lymphoma, lymphoblastic lymphoma, cutaneous T-Cell lymphoma and lymphoplasmacytic lymphoma (LPL)/ Waldenstrom's macroglobulinemia (WM) will be excluded.

• Patients must not be candidates for hematopoietic cell transplant (HCT) at the time of screening.

• AML (only for Group 3): Patients relapsed on or refractory to venetoclax containing regimens.

Additional requirements for specific disease conditions are:

• CLL/SLL: Peripheral blood lymphocytosis (with no other cause), CLL present on BM aspirate, or enlarged lymph node (LN), liver or spleen.

• Lymphoma (Except for other leukemias): At least one measurable or evaluable lesion as defined by the Lugano (2014) response criteria. Patients must have received at least 2 prior lines of systemic therapy.

• AML, Cohort 4 (ASXL1 mutations): AML patients relapsed on and/or refractory to therapies containing venetoclax combinations and with documented ASXL1 mutation.

• AML, Cohort 5 (Other than ASXL1 Myelodysplasia related AML defining somatic mutations): AML patients relapsed on and/or refractory to therapies containing venetoclax combinations and with documented Defining somatic mutations, Cytogenetic abnormalities defining acute myeloid leukemia, myelodysplasia related, other than ASXL1 mutation per WHO 5th Edition classification.

Mutations in Cohort 5 include: BCOR, EZH2, SF3B1, SRSF2, STAG2, U2AF1 and ZRSR2.If any of those mutations is present concurrently with ASXL1 mutation, patients will be enrolled in Cohort 4 (ASXL1 mutation) and only patients harboring the above listed mutations without concurrent ASXL1 mutation will be enrolled in Cohort 5 (Other than ASXL1 Myelodysplasia related AML defining somatic mutations).

3. Life expectancy ≥ 12 weeks.

4. The following hematological clinical laboratory results during screening:

For lymphoma, CLL/SLL patients:

• Absolute neutrophil count: for lymphoma ≥ 1,000/µL without growth factor support in the 2 weeks prior to study entry; for CLL/SLL, ANC must be ≥ 500/µL if myelosuppression is known to be due to BM involvement with leukemia.

• Hemoglobin ≥ 7.5 g/ dL without transfusion or erythropoietin treatment in the 2 weeks prior to study entry. Patients with BM involvement will not have the threshold of hemoglobin at screening.

• Platelet count ≥ 50,000/µL without transfusion or other interventions in the 2 weeks prior to study entry.

For Groups 4 and 5:

Patients eligible for inclusion must meet all of the following criteria:

1. For Group 4: newly diagnosed AML patients who must meet 1 or more of the following 3 criteria:

• AML patients with AML MR (AML myelodysplasia related) as defined by WHO 5th Edition (The 5th edition of the World Health Organization Classification of Hematolymphoid Tumors: Myeloid and Histiocytic/Dendritic Neoplasms). Mutations include: ASXL1, BCOR, EZH2, SF3B1, SRSF2, STAG2, U2AF1, and ZRSR2. Cytogenetic changes include: complex karyotype, 5q deletion or loss of 5q due to unbalanced translocation, monosomy 7, 7q deletion, or loss of 7q due to unbalanced translocation, 11q deletion, 12p deletion or loss of 12p due to unbalanced translocation, monosomy 13 or 13q deletion, 17p deletion or loss of 17p due to unbalanced translocation, isochromosome 17q, idic(X)(q13)); and/or

• AML MM (AML with myelomonocytic/ myelomonoblastic differentiation per FAB M4/M5) and/or

• Mayo 2024 HR/VHR (Mayo Genetic Risk Models for Newly Diagnosed Acute Myeloid Leukemia Treated With Venetoclax + Hypomethylating Agent. High Risk is defined as ≥2 points where points are: ELN 2022 Adverse Karyotype: 1 point; IDH2wt: 1 point; TP53mut: 1 point; KRASmut: 1 point; KMT2A rearrangement: 2 points).

2. Group 5: First-line AML patients who have failed to achieve CR, CRi, or MLFS after the first 2 cycles of azacitidine/venetoclax (defined as ≥5% blasts in bone marrow or presence of circulating blasts after 2 cycles of azacitidine and venetoclax).

3. Life expectancy ≥6 weeks.

Exclusion Criteria

For Groups 1, 2, 3, 4 and 5:

Patients eligible for inclusion must not meet any of the following criteria:

1. Uncontrolled medical conditions such as hypertension (systolic blood pressure > 160 mmHg and/or diastolic blood pressure > 100 mmHg), a history of hypertensive crisis, or a history of hypertensive encephalopathy.

2. History of previous exposure to any other CDK9 inhibitors.

3. Known hypersensitivity to the study drug or excipients of the preparation or any agent given in association with this study.

4. Severe cardiovascular disease within 6 months of study entry, including any of the following:

• Clinically significant heart disease such as congestive heart failure requiring treatment (NYHA class III or IV), left ventricular ejection fraction (LVEF) < 50% as determined by MUGA scan or echocardiogram (ECHO), (if only with historical occasional low LVEF but without any symptoms or relevant medical history, and the LVEF at screening is > 50%, the subject is eligible), or clinically significant arrythmia.

• History/evidence of acute coronary syndromes (including myocardial infarction, unstable angina, coronary artery bypass graft (CABG), coronary angioplasty, or stenting).

• Average QTcF ≥ 450 msec (males) or ≥ 470 msec (females) on screening ECG.

• Moderate or above regurgitation on echocardiogram

5. Patients with prior treatment with cardiotoxic agents who have experienced drug induced cardiotoxicities during or after treatment, where cardiotoxic agents include but are not limited to anthracyclines (doxorubicin, daunorubicin, epirubicin, idarubicin, mitoxantrone); trastuzumab and trastuzumab based ADCs; tyrosine kinase inhibitors (sunitinib, imatinib); alkylating agents (cyclophosphamide).

6. Patients who are on systemic antibiotics are eligible to participate as long as the antibiotics are not expected to have significant DDI with GFH009 (A list of approved concomitant medications will be provided to investigators. If any antibiotic is not included in the approved list, it can be discussed with the sponsor or designated CRO on a case-by-case basis).

7. Active hepatitis B or hepatitis C virus infection. Patients with chronic HBV infection with active disease who meet the criteria for anti HBV therapy have to be on a suppressive antiviral therapy prior to enrollment.

Patients with HCV may be enrolled if the HCV is stable, and the patient is not at risk for hepatic decompensation.

Patients with known HIV infection except if:

• They have CD4+ T-cell (CD4+) counts ≥ 350 cells/uL, and

• No history of AIDS-defining opportunistic infections within the last 12 months preceding screening, and

• Are on established ART for at least four weeks and have an HIV viral load less than 400 copies/mL prior to enrollment.

8. Concomitant medications that are strong CYP3A4 inhibitors or strong inducers within 7 days prior to the first dose. Avoid consumption of Seville orange (and juice), grapefruit or grapefruit juice, grapefruit hybrids, pomelos, star citrus fruits or St. John's wort within 7 days of first dose.

9. Stroke or intracranial hemorrhage within 6 months.

10. Major surgery within 4 weeks prior to study entry.

11. Pregnant or breast-feeding females.

12. Prior allogeneic stem cell transplant within 6 months of study entry. Patients who received autologous HCT, if considered to be enrolled and must be > 3 months post-transplant and meet hematologic inclusion criteria.

13. Any uncontrolled intercurrent illness or condition that in the judgement of the investigator may endanger the patient.

14. Medications that are known to prolong the QT interval that could not be stopped prior to study entry judged by investigator, except azole antifungal medications in AML patients.

For Groups 1, 2 and 3:

Patients eligible for inclusion must not meet any of the following criteria:

1. For AML and other leukemias: Systemic chemotherapy or demethylating agent therapy within 7 days, or targeted therapy within 7 days or 5 half-lives whichever is shorter, or immunotherapy within 4 weeks, or CAR-T therapy within 12 weeks before the first dose. If a patient is receiving high dose cytarabine, liposomal cytarabine, or standard dose cytarabine (100-200 mg/m2/day), the patient must be off the drug for at least 2 weeks or until the patient has recovered from toxic effects. Patients in Group 3 are allowed to have received venetoclax and/or hypomethylating agents (HMAs) prior to screening and will continue receiving venetoclax in combination with azacitidine throughout the duration of the trial. No washout from HMAs and/or venetoclax is required for this group.

For lymphoma and CLL/SLL: Patients who have received chemotherapy or targeted therapy within 4 weeks (6 weeks for nitrosourea or mitomycin-C) or 5 half-lives whichever is shorter, or immunotherapy (e.g., CD20 monoclonal antibody, CD38 monoclonal antibody, PD1 or PD-L1 antibody) within 4 weeks, or CAR-T therapy within 12 weeks prior to starting study drug.

2. Patients with bulky disease (≥ 10 cm) who require cytoreductive therapy.

3. Radiotherapy with wide field radiation within 28 days or radiotherapy with a limited field of radiation for palliation within 7 days of the first dose.

4. Symptomatic central nervous system (CNS) metastases or primary lymphoma such as primary CNS lymphoma, leptomeningeal disease, or spinal cord compression. Patients with asymptomatic CNS metastases who are radiologically and neurologically stable ≥ 4 weeks following CNS-directed therapy and are on a stable or decreasing dose of corticosteroids are eligible for study entry.

5. Ongoing therapy with corticosteroids greater than 20 mg of prednisone or its equivalent per day. Inhaled and topical steroids are allowed.

6. Patients with a baseline cardiac biomarker abnormality (CKMB/cTnI) will be excluded.

7. Patients with hypereosinophilic syndrome defined as eosinophil counts in peripheral blood of ≥1,500/µ.

8. Pulmonary embolism within 6 months before study entry. Patients with a history of other clinically venous or arterial thrombotic events that the investigator feels puts the patient at risk for participation in the study (based on overall status, medical history, or other factors) will be excluded.

9. Concurrent malignancy within 5 years (for AML patients, 2 years) prior to entry other than adequately treated cervical carcinoma-in-situ, localized squamous cell cancer of the skin, basal cell carcinoma, prostate cancer not requiring treatment, ductal carcinoma in situ of the breast, and superficial non-muscle invasive urothelial carcinoma (excluding T1 lesions and CIS).

10. For AML patients only: Given that GFH009 is a CYP3A4 substrate and the critical role of azole antifungals (commonly strong CYP3A4 inhibitors) in the treatment of patients with AML, if use of azole antifungals is necessary for the patients in AML post-transplant and meet hematologic inclusion criteria.&#xd; &#xd;

11. Any uncontrolled intercurrent illness or condition that in the judgement of the&#xd; investigator may endanger the patient.&#xd; &#xd;

12. Medications that are known to prolong the QT interval that could not be stopped&#xd; prior to study entry judged by investigator, except azole antifungal medications in&#xd; AML patients.&#xd; &#xd; For Groups 1, 2 and 3:&#xd; &#xd; Patients eligible for inclusion must not meet any of the following criteria:&#xd; &#xd;

13. For AML and other leukemias: Systemic chemotherapy or demethylating agent therapy&#xd; within 7 days, or targeted therapy within 7 days or 5 half-lives whichever is&#xd; shorter, or immunotherapy within 4 weeks, or CAR-T therapy within 12 weeks before&#xd; the first dose. If a patient is receiving high dose cytarabine, liposomal&#xd; cytarabine, or standard dose cytarabine (100-200 mg/m2/day), the patient must be off&#xd; the drug for at least 2 weeks or until the patient has recovered from toxic effects.&#xd; Patients in Group 3 are allowed to have received venetoclax and/or hypomethylating&#xd; agents (HMAs) prior to screening and will continue receiving venetoclax in&#xd; combination with azacitidine throughout the duration of the trial. No washout from&#xd; HMAs and/or venetoclax is required for this group.&#xd; &#xd; For lymphoma and CLL/SLL: Patients who have received chemotherapy or targeted&#xd; therapy within 4 weeks (6 weeks for nitrosourea or mitomycin-C) or 5 half-lives&#xd; whichever is shorter, or immunotherapy (e.g., CD20 monoclonal antibody, CD38&#xd; monoclonal antibody, PD1 or PD-L1 antibody) within 4 weeks, or CAR-T therapy within&#xd; 12 weeks prior to starting study drug.&#xd; &#xd;

14. Patients with bulky disease (≥ 10 cm) who require cytoreductive therapy.&#xd; &#xd;

15. Radiotherapy with wide field radiation within 28 days or radiotherapy with a limited&#xd; field of radiation for palliation within 7 days of the first dose.&#xd; &#xd;

16. Symptomatic central nervous system (CNS) metastases or primary lymphoma such as&#xd; primary CNS lymphoma, leptomeningeal disease, or spinal cord compression. Patients&#xd; with asymptomatic CNS metastases who are radiologically and neurologically stable ≥&#xd; 4 weeks following CNS-directed therapy and are on a stable or decreasing dose of&#xd; corticosteroids are eligible for study entry.&#xd; &#xd;

17. Ongoing therapy with corticosteroids greater than 20 mg of prednisone or its&#xd; equivalent per day. Inhaled and topical steroids are allowed.&#xd; &#xd;

18. Patients with a baseline cardiac biomarker abnormality (CKMB/cTnI) will be excluded.&#xd; &#xd;

19. Patients with hypereosinophilic syndrome defined as eosinophil counts in peripheral&#xd; blood of ≥1,500/µ.&#xd; &#xd;

20. Pulmonary embolism within 6 months before study entry. Patients with a history of&#xd; other clinically venous or arterial thrombotic events that the investigator feels&#xd; puts the patient at risk for participation in the study (based on overall status,&#xd; medical history, or other factors) will be excluded.&#xd; &#xd;

21. Concurrent malignancy within 5 years (for AML patients, 2 years) prior to entry&#xd; other than adequately treated cervical carcinoma-in-situ, localized squamous cell&#xd; cancer of the skin, basal cell carcinoma, prostate cancer not requiring treatment,&#xd; ductal carcinoma in situ of the breast, and superficial non-muscle invasive&#xd; urothelial carcinoma (excluding T1 lesions and CIS).&#xd; &#xd;

22. For AML patients only: Given that GFH009 is a CYP3A4 substrate and the critical role&#xd; of azole antifungals (commonly strong CYP3A4 inhibitors) in the treatment of&#xd; patients with AML, if use of azole antifungals is necessary for the patients in AML&#xd; groups, and if azoles cannot be substituted with alternative antifungal drugs (e.g., caspofungin, amphotericin B etc.), use of isavuconazole, the only azole antifungal that is a moderate CYP3A4 inhibitors and does not prolong QT interval, is recommended. Other azoles are allowed if deemed necessary by the investigator. If azoles are used, AML patients receiving azole antifungals will be subject to enhanced monitoring plan provided in section 6.5.2. PK of GFH009 will be compared in patients with coadministration of azole antifungals versus those without azole antifungals.

23. Subjects with high risk of gastrointestinal hemorrhage, including but not limiting to active ulcer with fecal occult blood test ≥++; history of hematemesis or melena within 2 months prior first dose.

For Groups 4 and 5:

Patients eligible for inclusion must not meet any of the following criteria:

1. For patients in Group 4, no prior anti-leukemic therapy is allowed, except for ATRA if used for suspected APL, or hydroxyurea or cytarabine if used emergently for emergent cytoreduction or disease stabilization (a maximum total cumulative dose of cytarabine 1 g).

For patients in Group 5, no prior antileukemic therapy except venetoclax and azacitidine for exactly 2 cycles is allowed prior to screening. Patients will continue receiving venetoclax in combination with azacitidine throughout the duration of the trial. No washout from azacitidine and venetoclax is required.

2. For AML Group 4: presence of favorable risk cytogenetic markers including: NPM1-mutations (with FLT3-ITDneg, NRASwt, KRASwt, TP53wt); IDH2-mutations (with FLT3-ITDneg, NRASwt, KRASwt, TP53wt); IDH1-mutations (with TP53wt); AML with DDX41-mutations is excluded.

3. Patients with a history of clinically significant venous or arterial thrombotic events that the investigator feels puts the patient at risk for participation in the study (based on overall status, medical history, or other factors) will be excluded.

4. Concurrent malignancy within 2 years prior to entry other than adequately treated cervical carcinoma-in-situ, localized squamous cell cancer of the skin, basal cell carcinoma, prostate cancer not requiring treatment, ductal carcinoma in situ of the breast, and superficial non-muscle invasive urothelial carcinoma (excluding T1 lesions and CIS).

5. Concurrent malignancy within 2 years prior to entry other than adequately treated cervical carcinoma-in-situ, localized squamous cell cancer of the skin, basal cell carcinoma, prostate cancer not requiring treatment, ductal carcinoma in situ of the breast, and superficial non-muscle invasive urothelial carcinoma (excluding T1 lesions and CIS).

6. Given that GFH009 is a CYP3A4 substrate and the critical role of azole antifungals (commonly strong CYP3A4 inhibitors) in the treatment of patients with AML, if use of azole antifungals is necessary for the patients in AML groups, and if azoles cannot be substituted with alternative antifungal drugs (e.g., caspofungin, amphotericin B etc.), use of isavuconazole, the only azole antifungal that is a moderate CYP3A4 inhibitors and does not prolong QT interval, is recommended. Other azoles are allowed if deemed necessary by the investigator.